The irony here is that camless engines are relatively easy to build. The average hacker could modify a small four-stroke engine for camless. The latest to catch my attention: engine valves that operate without camshafts. For decades the idea of electronically controlled electromagnetic. The “camless” engine developed by Koenigsegg sister company FreeValve edged closer to production on Friday with Qoros’ unveiling of a.
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The modern internal combustion engine is a marvel of engineering. The irony here is that camless engines are relatively easy to build. The average hacker could modify a small four-stroke engine for camless operation in their workshop. A multi-cylinder gasoline engine is a complex dance.
Hundreds of parts must move in synchronicity. Valves open and close, injectors mist fuel, spark plugs fire, and pistons move up and down. Lobes on the shaft press on tappets which then move the valve stems and the valves themselves. The camshaft itself is driven at half the speed of the crankshaft through timing gears, chains, or a belt. Some valve trains are relatively simple — such as overhead cam engines.
Others, such as the cam-in-block design, are more complex, with pushrods, rockers, and other parts required to translate the movement of the cam lobe to movement at the valve. Exactly when, and how fast a valve opens is determined by the profile of the cam lobe. Everything comes at a cost though.
Camless piston engine – Wikipedia
Too aggressive a lobe profile can lead to valve float, where the valves never fully seat at high RPM. Engine manufacturers have spent years working around the limitations of the camshaft. The results are myriad caless solutions. All these systems provide ways to adjust the valve action to some degree. VANOS works by allowing the camshaft to slightly rotate a few degrees relative to its normal timing, similar to moving a tooth or two on the timing chain.
While these systems do work, they tend to be mechanically complex, and expensive to repair.
The simple solution would be to go with a camless engine. This would mean eliminating the camshaft, timing belt, and most of the associated hardware. Solenoids or hydraulic actuators open and close the valves in an infinitely variable number of ways. There are a few reasons. The advantages of camless engines to camshaft engines are analogous to the advantages of electronic fuel injection EFI vs carburetors.
At the core, a fuel injector is a solenoid controlled valve. The fuel pump provides constant pressure.
The engine control unit ECU fires the injectors at just the right time to inject fuel into the cylinders. The computer also leaves the valves open long enough so that the right amount of fuel is injected for the current throttle position. Electronically this is very similar to what would be required for a camless engine. Making a clean, fuel-efficient carbureted engine was possible, but there were so many mechanical and electronic actuators required that the EFI was a better alternative.
All the big manufacturers have experimented with the camless concept. The best effort to date has been from Freevalve, a subsidiary of Koenigsegg.
They have a prototype engine running in a Saab. LaunchPoint Technologies have uploaded videos showing some impressive actuator designs LaunchPoint is working with voice coils, the same technology which moves the heads in your hard drive.
However, these are giant diesel engines used to drive large ships or generate power. For the hacker set, the best way to get your hands on a camless engine today is to hack one yourself.
Simple, single-cylinder camless engines are relatively easy to build. Start with a four stroke overhead valve engine from a snowblower, scooter, or the like.
Make sure the engine is a non-interference model. This means that it is physically impossible for the valves to crash into the ebgine. Add a power source and some solenoids. Examples are all over the internet. The control system is a mechanical wheel with electric contacts, similar to a distributor cap and rotor system. Note that this project uses two solenoids — one to open and one to close the valve. This route is an excellent stepping stone before making the jump to full electronic control.
Formula 1 engines are all camless, they use pneumatic valve actuators, so they can turn at up to 20, rpm usually more like 12, for caamless efficiency.
The current formula limits engine RPM to 15, rpm section 5. Also, they still use cams. This is due primarily to section 5. They use pneumatic valve springs. They have cams like a normal engine. The use of pneumatic valve springs plus a short stroke allows the high engine RPM. The Fiat Multiaire system — if this is what you are getting at in a round about way — is a consumers nightmare.
The system consumes oil and is very unpredictable under certain stress conditions. Egnine should be eliminated and outlawed. Or just keep it in Italy. I think that camless engine technology is like any other engine improvement tech: Right, good enough and cheap will always win out over perfect and expensive unless there is something that makes good enough more expensive.
Electric solenoid valve actuators were in Hot Rod magazine in the s. Never panned out back then. Things are better now. If you can think it, you can do it. The difficulty was and is achieving effective seals. The more modern way of solving valve bounce issues is to move away from poppets to desmodronics, but that adds complexity on the flipside it reduces friction dramatically.
A poppet valvetrain is one of the largest frictional components in any engine. You might think of these dual-solenoid setups as a kind of electronically actutated desmodronic system.
Pneumatic assisted cams are already in production cars. Fiat have them on the Twin-Air units with some electronic controls to allow things like double valve opening during the compression stroke. WRT keeping the valves open to deactivate cylinders: This was evaluated when various makers started producing engines in the s and it was found to be more efficient to keep them closed, using the cylinder as an air spring.
Cad, Chrysler C and others.
Where are all the Camless Engines?
The rotary I saw run was a Detroit Diesel 2 stroke converted to a four stroke, custom head, with a rotary valve running on a belt, A bar with a slot in it turboed, and it camles. The application was APU for the military. Old style rotary sleeve valves were driven from below.
Broken wire, excessive heat build up, wear from sliding surfaces. Pot the solenoid, over-spec it for the duty cycle, use a low friction liner, perhaps some sort of oil-impregnated piston. And then your electronics fail and ram your valves into your piston, because non-interference designs are highly inefficient and impractical. Um… cars already have electronics.
The probablility of failure may be low but the cost of damage is high.
I would love to see a camless engine myself but no system is flawless. Every system has its limits. In a non-interference engine failure would have no ill effect, other than no or poor compression in that cylinder.
Except the current electronics will not BLOW or otherwise damage the mechanics when they fail. Having an exhaust valve stuck closed can put way too much pressure on the exhaust cycle turning it into another compression, but where the starting pressure is much higher than intake ending.
That would instantly stall an unloaded engine. This is another technology I will camlss trust, just like electronic brakes and steering not electronically assisted…. If anybody tells you they figured all the ways a SW can fail, it means the SW is pretty simple. Lots of physical reasons for this not being true. Fuel injects are solenoids, and valve lifters can be mad of solenoids, so their MTBF ought to be the same.
The fuel injector valve is VERY small. The mechanical stopper itself is possibly half a mm. The solenoid coil is smaller than a pea. The total weight to move is measured in mg. The only real work being done is against the fuel pressure.
The stroke of the solenoid is fractions of a mm. Activation current is really camlese. Now the valve lifter: Large valve surfaces against pressurized gas explosions. The whole mechanism is MUCH larger. Factor of 10 at least.